Starting 2008, he spent time with KHL teams HC Dinamo Minsk, Lokomotiv Yaroslavl, Traktor Chelyabinsk and Avangard Omsk.

Mezin gained international attention in 2002 as a member of the Belarus national men's ice hockey team at the 2002 Winter Olympics.

Despite not winning a game in the Group D round robin, Belarus beat the Sweden national men's ice hockey team in the quarterfinals.

The game was won by Belarus late in the third on a long shot gaffe made by Tommy Salo in the Swedish net.

On 1 October 2008 Mezin and Metallurg Magnitogorsk faced the New York Rangers of the NHL in the inaugural Victoria Cup.